OBSERVATIONS ON FLORAL CHANGES. 



79 



In taking even a cursory survey of the vegetation of the globe, no one 

 can fail to discern many of the grand purposes for which the all-wise Creator 

 has adorned the earth with so rich a profusion of plants, varying in form and 

 habits to suit all the circumstances of soil and climate which occur in the 

 natural course of things. One of these purposes we often see beautifully 

 exemplified in the manner in which an island or tract of country suffering 

 change in circumstances affecting vegetable life, becomes speedily inhabited by 

 races of plants suited to the new conditions. An island rises from the bosom 

 of the waters: how soon does it exchange its clothing of sea-weeds for one of 

 green herbage and flowers! a mountain side loses its dense forest; how soon 

 do the hardy mountain plants occupy the places of those which luxuriated in 

 the nursing shade and shelter of the forest boughs! a barren sandy desert is 

 overflown by springs; how soon is their fertilizing influence indicated by a 

 rich growth of luxuriant vegetation, exhibiting forms which were wholly absent 

 before! 



Without referring to the results of geological research, we can readily trace 

 constant changes of a truly natural character going on in every land, resulting 

 from the modifying influences of soil, climate, physical character, and other 

 circumstances. The animal creation has likewise powerful influences on the 

 vegetation of a country; and we can easily see some of these influences without 

 referring to such notions as those which regard the feathered tribes as guided 

 by instinct, to propagate particular plants which afford them food. In a 

 country like ours, universally cultivated, and bearing every characteristic of a 

 high degree of civilization, the floral changes resulting from the operations of 

 man strike us as infinitely greater than those caused by the lower animals, 

 whose influences, moreover, are in such a case greatly weakened; and hence, 

 undoubtedly, arises the disposition to regard changes brought about by man's 

 presence, as really distinct in character from those arising from other operative 

 natural causes. We cannot, however, see upon what principle man's physical 

 influences can be held to be at variance with the order of nature — as if, 

 forsooth, he were an intruder upon this earth of ours, holding no title to play 

 his important part in physical changes, which are even participated in, and 

 influenced by, the most minute and simple organisms which the microscope 

 has made known to us. 



Sir Charles LycU, in his "Principles of Geology," offers some excellent 

 observations in point, in reference to the animal kingdom, which apply with 

 equal force to the case of vegetables. ,He says, ^'The modifications in the 

 system of which man is the instrument, do not, in all probability, constitute 

 so great a deviation from analogy as we usually imagine; we often, for example, 

 form an exaggerated estimate of the extent of the power displayed by man 

 in extirpating some of the inferior animals, and causing others to multiply; 

 a power which is circumscribed within certain limits, and which, in all like- 

 lihood, is by no means exclusively exerted by our species. The growth of 

 human population cannot take place without diminishing the numbers, or 



